But it's cut off from oil because other countries refuse to trade with Cuba. Not because the US Navy is blocking vessels (besides those flying false flags) from docking with Cuba.

If you really believe there's no distinction between an embargo and a blockade then you should have just correctly used the term "embargo". This isn't pedantry, this is the difference between an act of war and an economic move.

I would further note that, if one is looking for something to dislike about the embargoes, being a blockade isn't necessary. In particular, (classical) liberals should be disturbed by countries forcing private shippers to participate in "their" country's embargo. E.g., would the US attempt to stop and American company from trading with Cuba?